On the contrary, different from other NDAFs with high expression in the early or late infection period, the level of major components of tight junction proteins of the BBB, claudin-5, had slightly increased in mice with medium- and high-dose infections, reaching 1.68- and 1.46-fold at 8 wpi (P > 0.05), respectively (Fig. 5f). This evidence concerns the gene CLDN5 and infection.